Abstract
Arabidopsis has 12 histone acetyltransferases grouped in four families: the GNAT/HAG, the MYST/HAM, the p300/CBP/HAC and the TAFII250/HAF families. We previously showed that ham1 and ham2 mutants accumulated higher damaged DNA after UV-B exposure than WT plants. In contrast, hag3 RNA interference transgenic plants showed less DNA damage and lower inhibition of plant growth by UV-B, and increased levels of UV-B-absorbing compounds. These results demonstrated that HAM1, HAM2, and HAG3 participate in UV-B-induced DNA damage repair and signaling. In this work, to further explore the role of histone acetylation in UV-B responses, a putative function of other acetyltransferases of the HAC and the HAF families was analyzed. Neither HAC nor HAF acetyltrasferases participate in DNA damage and repair after UV-B radiation in Arabidopsis. Despite this, haf1 mutants presented lower inhibition of leaf and root growth by UV-B, with altered expression of E2F transcription factors. On the other hand, hac1 plants showed a delay in flowering time after UV-B exposure and changes in FLC and SOC1 expression patterns. Our data indicate that HAC1 and HAF1 have crucial roles for in UV-B signaling, confirming that, directly or indirectly, both enzymes also have a role in UV-B responses.
Highlights
Posttranslational modifications of histones, including acetylation, are critical mechanisms that affect different aspects of plant growth and development (Kouzarides, 2007)
We showed that histone H3 and H4 acetylation is increased by UV-B radiation in maize and Arabidopsis plants; and plants treated with an inhibitor of histone acetylases showed increased DNA damage by UV-B (Casati et al, 2008; Campi et al, 2012)
We demonstrated that histone acetyltransferases from the HAG and HAM families participate in different responses of Arabidopsis plants exposed to UV-B radiation
Summary
Posttranslational modifications of histones, including acetylation, are critical mechanisms that affect different aspects of plant growth and development (Kouzarides, 2007). These modifications alter the chromatin structure, and have an essential role in DNA metabolism. Histone acetyltransferases regulate the acetylation of histones and other proteins such as transcription factors, affecting chromatin organization, transcriptional regulation, and DNA metabolism in general. Acetylated lysines at the amino-terminal histone tails change histone–DNA interactions and make the DNA more accessible (Kouzarides, 2007). These changes in histone acetylation/deacetylation are essential for the regulation of gene expression
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